Understanding Quantum Entanglement - with Philip Ball

Last year, Phil Ball gave a very popular talk at the Ri about quantum mechanics, here's his follow up on quantum entanglement, and our friends Alice and Bob.
Subscribe for regular science videos: bit.ly/RiSubscRibe
Watch the talk that started the conversation: • Why Everything You Tho...
---
A very special thank you to our Patreon supporters who help make these videos happen, especially:
Alessandro Mecca, Ashok Bommisetti, bestape, David Lindo, Elizabeth Greasley, Greg Nagel, John Pollock, Lester Su, Osian Gwyn Williams, Radu Tizu, Rebecca Pan, Roger Baker, Sergei Solovev, and Will Knott.
---
The Ri is on Patreon: / theroyalinstitution
and Twitter: / ri_science
and Facebook: / royalinstitution
and Tumblr: / ri-science
Our editorial policy: www.rigb.org/home/editorial-po...
Subscribe for the latest science videos: bit.ly/RiNewsletter

[@najibzaoui4073]

Bro, two paticles being actually the same one regardless of the distance is actually a more astonishing explanation than spooky action at a distance.

[@philipball4720]

I'm so glad you think so, because I agree. And also more correct, breaking no laws of physics.

[@SteelBlueVision]

Yes, except they have opposite properties in QM, so therefore, they cannot be the same particle

[@harlesbalanta2299]

Agree with steelbluevision, this are not the same particle,

[@markscience1]

@@philipball4720 But is not the concept of the two "entangled" particles being the same object also merely an analogy that helps our four dimensional brains try to make sense of a phenomenon that we are presently unable to make sense of? Are the two particles actually one in a dimension of which we are unaware, so that they are not distant from each other in that dimension but, rather, "touching" (yet another analogy, I guess)?

[@philipball4720]

@@SteelBlueVision No, they are not really "the same particle", I should have specified that. They are described by a single wave function.

[@aem0117]

This guy should be proud to be one of the best teachers around. He is able to explain complicated concepts unlike most any other person. Kudos.

[@monsieurmitosis]

This guy really is so great. The remote lecture he gave on quantum weirdness is the best introduction to the subject anyone could ever do.

[@KieranGarland]

Love the RI videos more than I can say. Keep 'em coming!

[@charlesdahmital8095]

Since we have moved on to rabbits and dogs, Am I to assume Schrodinger's cat is dead?

[@lexl1756]

hahaha!

[@DasSlime]

I think they just didn't want to risk youtube age-restricting the video on the off chance that it was dead. Opening the box beforehand would have ruined the experiment.

[@gazmasonik2411]

Oh No! The Mammals are all alike even extinct ones. Entropic empathy is illusion of expectation or latency in lactating this case not weighted 🤦‍♀️🤷‍♀️

[@zainabalshammari]

lool was it ever alive anyway?

[@nevermind-he8ni]

@MomoTheBellyDancer It's resting!

[@Weaver2600]

Thank you Phil. I also didn’t understand the example in the initial lecture, so I found this and now understand it. This is a fault with me not you. If my brain was a bit faster I would have understood it in the first place. QM is one of the most fascinating disciplines I have ever ventured into.

[@albdim1]

I adore the clarity of your explanations.

[@adamkhan838]

‘And then I entered into a quantum entanglement with August’

[@SiggaMaya]

I for one am astounded and amazed at these teaching skills- I can´t believe that I- as a somewhat logically challenged and abstract minded and scatterbrained layperson- managed to follow through this lecture and actually felt like I grasped the concepts! Well done!

[@grandaddennis]

He lost me at "hello"

[@loezperisoni9205]

ahahahah

[@jgrab1]

To me these "simplified" demonstrations and analogies often make it harder to understand than just talking about what's really going on.

[@seabud6408]

He lost me between “H ...” and “... o”

[@musicbro8225]

Perhaps you are quantumly entangled with him, such that when he knows, you don't know? The when he wishes to know what you know, he is lost, but you know :|

[@davidwright8432]

thanks! A very helpful clarification. Also, I like the book, having followed our suggestion and got it.

[@GulzarAhmad-sw1kh]

Excellent 👌! I appreciate the enthusiasm you have about QM.

[@allmhuran]

At 9:14 no coherent explanation is given as to why you are producing rabbits for Bob in Alice's 2 pound column. Sure, there's a bit of word salad thrown into the world as if it was a necessity that this be the case, but given the information provided up to that point in the video, nothing compels rabbits in Alice's 2 pound column. Note that I am not claiming that the conclusion is false. I am saying that the logic of the analogy is incoherent. It's perfectly possible to reach a true conclusion from invalid reasoning, but it doesn't help anyone else understand why the conclusion is true! I will provide the required logic to reach the (as it happens, true) conclusion at the end of this comment. The explanation provided was this combination of sentences: 1) "If alice has produced a rabbit with one pound, then the only way we can get a dog is if they both put in 2 pounds. 2) So alice has already put in 1 pound. 3) So bob's box has to produce a rabbit in both of those cases". Statement 1 is contains a non sequitur and is incoherent. If alice has put in one pound, then alice cannot have put in two pounds. There is no "if - then" relationship between the first and second part of the sentence because they describe two completely different cases. You can't create an "if-then" relationship between a case where Alice has put in 1 pound and a case where alice has put in two pounds. The second part of the sentence (1) is false. It is not true that the only way we can get a dog is if they both put in two pounds. We can also get at least one dog if alice puts in 2 pounds and bob puts in 1 pound, and two dogs result. This still satisfies all three rules. Statement (2) is just restating the premise, ie, we are looking at the scenario where alice has put in 1 pound. No problem here, but be careful with use of the word "so....". When making a logical argument, "so..." implies "what I am about to state follows from that which I have just stated", ie, it's often used as a synonym for "therefore". But statement 2 doesn't follow logically from statement 1, therefore use of the word "so..." is confusing. Statement (3) is unclear about which two cases are implied by "both". There are two axes here, the bob axis and the alice axis. If "both" means "both when bob puts in 1 pound, and when bob puts in 2 pounds", then the statement is correct. If alice has put in one pound, then in both of those cases bob must produce a rabbit. But in the graphic, you filled in both of those cases, AS WELL AS both cases where alice puts in 2 pounds. This is "both boths", as it were, and is not justified by the rules. These are the reasons why your explanation is considered unhelpful. Nobody can follow the logic because the logic isn't valid. The resolution to the invalidity is to bring in rule 4, which is the "NB" in italics in the rule slide, but which you do not actually state. That rule *seems* to mean that one box must always produce the same output for a given input. IE, it cannot be the case that bob's box can produce a rabbit on a 1 pound input on some occasions, and can also produce a dog on a 1 pound input.on other occasions. If that is the case then we cannot produce two dogs with the combination (alice 2, bob 1) as I previously suggested, because we have established that the combination (alice 1, bob 1) must produce (rabbit, rabbit) from the combination of rules 1 and 3, so (bob 1) -> rabbit, so we cannot also have (bob 1) -> dog. But this critical part of the logic is *never stated* during your explanation.

[@ThePinkus]

My understanding of how we get to 9:35 is in the following steps. Using the notation 1A for 1 pound in A and RA for rabbit in A, etc. Rule 1A -> RA yields the table (RA & ?) ? (RA & ?) ? Rule 1A&1B -> (RA & RB) or (DA & DB) yields (RA & RB) ? (RA & ?) ? Rule 1A&2B -> (RA & RB) or (DA & DB) yields (RA & RB) ? (RA & RB) ? Now, classical mechanics yields (RA & RB) (? & RB) (RA & RB) (? & RB) The not explicit point is that we are testing classical mechanics against the rules! Classical independent boxes imply that if we get RA then the whole column is RA, and if we get RB then the whole row is RB, likewise for D's. The reason being that what happens in A is not affected, i.e. column invariant, from what happens in B and vice versa, i.e. B is row invariant. That we are dealing with classical mechanics is mentioned later. This really got me lost the first time I watched the video, I thought at that point we were just applying the rules just stated. Incidentally, we can fill the table in 4 different ways that completely satisfy the rules IF we do not make any other assumption, but none of those solutions satisfy CM or QM. Ergo, the rules do not replicate QM, at least as I would intend the word "replicate".

[@RedAllStars2010]

Yes, no explanation. I think though in the 2nd column it could have come out a dog or a rabbit, but they've chosen just to put a rabbit as the choice. In the left hand column, the results have to be rabbits though, that bit was explained.

[@bill-zy6dg]

yes, clear as mud

[@Octotentaculaire]

Thank you so much, I didn’t realise the NB was important and just couldn’t make any sense out of his reasonning. This makes it all much clearer, good job.

[@irrelevant_noob]

allmhuran i think it's because of the 3rd rule: you're only allowed to get a Rabbit-Dog pair from the 2p+2p case, so when A used 1p (and got a Rabbit), B will need to also get rabbits. Regardless of which coin B used, they have to get a Rabbit. So for B, the outcome is always a Rabbit, and that is actually independent of A's coin, so it will also happen when A will use her 2p coin. But i agree tbere was no explanation provided in the video, i had to pause there and think about what and why is going on...

[@ASLUHLUHCE]

As commenter 'allmhuran' pointed out, the rather offhandedly included line, "NB - these are simple, unconnected mechanical boxes with one given output (animal) per input (coin)" was the single thing that had to be understood (and should've been explained) to make this analogy sensical.

[@chikkamurthy3404]

Excellent video.. i understood the whole phenomenon.. thank you sir.. your way of presenting was really good..

[@l.t.jameson4449]

Brilliant conversation Sir,,it seems to me we could expand our understandings of quantum entanglement by interjecting into the conversation models,and examples of the different types of electrons and how they function,AC/DC,,and differences between single phase electrical systems,and three phase electrical systems, such as Delta,and Y,, ..either way I love having and hearing these conversations.In doing so maybe one day we will be able to explain it and understand it in such a manner that we could at the least refrain ourselves from having Wars with each other.God Bless!

[@cugms]

Thank you for making this video. It's the best one I've seen on quantum entanglement, and I've seen a lot, trying to wrap my head around it!

[@hquillin]

I actually see this video as a book pitch and a good one.

[@tabaks]

Far, FAR from being the best.

[@cugms]

@@tabaks For example?

[@redfishervictoria]

Unfortunately Quantum does not exist and never has for science has proven that the smallest particle in the universe is the proton. Popular Science has even proven that they do not know what an electron is or even light. They have recently proven dark matter and energy does not exist. And the large colliders have proven that given enough energy a proton can be destabilized back into energy. The quantum particles are actually decaying matter back to energy. That is why these quantum particles only exist for Pico seconds or less! This is actually the time it takes for complete destabilization.

[@tabaks]

How appropriate to try explaining such a convoluted and hard to understand concept using a convoluted and hard to understand example. Bravo!

[@david203]

That is just what I thought. Analogies are wonderful when they are accurate but simpler, such as liquid flow through pipes in analogy to electric circuits in classical physics.

[@stringedassassin]

I love these vids and take the material seriously... I still smile when we discuss Alice's box though.

[@xmanlatter6013]

Thank you this is the best description of quantum entanglement I’ve seen👍🏾.

[@arctic_haze]

Great talk. And I like the final point a lot. Quantum mechanics is a window into a deeper theory, one where either time or space is emergent. And this 85% limitation may be a clue about what lies beyond it.

[@jasoncassidy492]

There is no such thing as time. It's a human invention based on the rotational period of the Earth. Psychological time is something we have developed related to our ability to store information in our memories but it too is an illusion represented as past and future. The only real state is here and now. Einstein was wrong when he claimed time can dilate. The inventor of the atomic clock, Louis Essen, claimed Einstein did not understand measurement. He also claimed relativity theory developed by Einstein is not even a theory, but a collection of thought experiments. Einstein arbitrarily added a multiplier to time in equations like s = vt to make it s = kvt, with no proof of that condition. it means not only time can change but distance too, as velocity increases toward the speed of light.

[@arctic_haze]

@@jasoncassidy492 You wrongly present your views on the subject of time as facts. There is no scientific consensus on this.

[@jasoncassidy492]

​@@arctic_haze ...these are not my views, they are fact. Time was invented by humans based on the period of rotation of the Earth. A period is not defined on time until someone supplies unit, like seconds. If you can find a phenomenon called time independent of the rotation of the Earth, please post it. Meantime, please consider why we have two forms of time, solar time and sidereal time. One is based on the exact period of rotation of the Earth from noon to noon and the other is based on the period of rotation wrt the stars. That's because the Earth moves a considerable distance around the Sun during a day, therefore one day is longer than the other. Then you might consider why time has an analog in the distance traveled by a point on the Equator. Time can also be expressed in minutes and seconds (arc length) and not in seconds of time. Therefore time can be a distance as well. I have discussed this with physicists. Some agree with me and the others become frustrated when they cannot find a time independent of the Earth's rotation. There are sure it is there but they cannot point to it.

[@arctic_haze]

@Jason Cassidy I already firgot what your views are. But you can easily measure time without using the Earth rotation. Look how the second is defined.

[@evelynday6219]

Definitely something going on when we turn our attention to measuring quantum objects, the double slit experiment also, our thoughts change particle behaviour somehow. Thankyou very much for hashing it out a bit more, it is a mind blowing concept, letting go of preconceptions and being amazed but something that is measurable and real is refreshing.

[@grantmcauliffe3437]

That is one of the best talks I've seen and heard. I studied QM at Uni, and his talk gave me a real insight into what I learned through number crunching the equations, but not really being able to form some sort of mental picture about what was going on in that weird QM space. It really is like a "Fairyland of Weirdness", if you study it. It's better than The Adventures of Alice In Wonderland. Bells Inequality and Bell's Theorem are mind bending concepts to get one's head around.

[@wmstuckey]

Philip Ball is one of the few people in foundations of physics who recognized the value of the quantum reconstruction program (QRP) early on. He was advocating for that approach as early as 2009 in a KZbin video and shared Dakic and Brukner's information-theoretic reconstruction in a KZbin video on quantum entanglement years ago. Well, it turns out Philip was prescient. Quantum information theorists have now rendered quantum mechanics (QM) a principle theory based on the relativity principle exactly like special relativity (SR), which shows QM is as complete as possible and totally compatible with SR (many believe quantum entanglement renders QM at odds with SR). With that understanding of QM one can rule out the existence of Popescu-Rohrlich joint probabilities (the PR-box) because they violate conservation per the relativity principle. We explain that in "Why the Tsirelson Bound? Bub’s Question and Fuchs’ Desideratum" Entropy 2019, 21(7), 69. We explain the conservation principle itself in "Answering Mermin’s challenge with conservation per no preferred reference frame" Scientific Reports volume 10, Article number: 15771 (2020). [Those are open access, but I can't provide the links or KZbin will delete this post.] Those articles are a bit technical, but we have it all explained for the "general reader" forthcoming in "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" due out in June 2024 with Oxford UP (see Chapter 8 specifically for the PR-box). Here's a brief summary. The mystery of quantum entanglement arises because we are looking for a 'causal mechanism' behind its correlations, what Einstein called "constructive efforts." Einstein was faced with a very similar situation concerning constructive accounts of length contraction (and time dilation) to explain the Michelson-Morley experiment. Einstein wrote: "By and by I despaired of the possibility of discovering the true laws by means of constructive efforts based on known facts. The longer and the more despairingly I tried, the more I came to the conviction that only the discovery of a universal formal principle could lead us to assured results." That is, he gave up looking for causal mechanisms ("constructive efforts") that would shrink meter sticks and slow down clocks to fool everyone into measuring the same value for the speed of light c, regardless of their relative motions (an empirically discovered fact known as the light postulate). Instead, he said c is a constant of Nature per Maxwell's equations, so the relativity principle -- the laws of physics (including their constants of Nature) are the same in all inertial reference frames -- demands that everyone measure the same value for c, regardless of their relative motions. The Lorentz transformations of SR follow from the light postulate as justified by the relativity principle. As it turns out, the same opportunity for QM has been provided by quantum information theorists. That is, they have reconstructed QM based on an empirically discovered fact called Information Invariance & Continuity that (in non-information-theoretic terms) means everyone measures the same value for Planck's constant h, regardless of their relative spatial orientations. How does that solve the mystery of quantum entanglement? Suppose you send a vertical spin up electron to Stern-Gerlach (SG) magnets oriented at 60 deg relative to the vertical. Since spin is a form of angular momentum, classical mechanics says the angular momentum you should measure is (hbar/2)cos(60) = hbar/4 in that direction of SG spatial orientation. But, the SG measurement of electron spin constitutes a measurement of h, so everyone has to get the same +/- hbar/2 for a spin measurement in any SG spatial orientation, which means you can't get what you expect from common sense classical physics. Instead, QM says the measurement of a vertical spin up electron at 60 deg will produce +hbar/2 with a probability of 0.75 and it will produce -hbar/2 with a probability of 0.25, so the average is (hbar/2 + hbar/2 + hbar/2 - hbar/2)/4 = hbar/4. In other words, quantum mechanics says you get the common sense classical result on 'average only' because of the observer-independence of h. Now suppose Alice and Bob are measuring the spin singlet state (the two spins are anti-aligned when measured in the same direction) and Alice obtains +hbar/2 vertically and Bob measures his particle at 120 deg relative to Alice. Obviously, if Bob had measured vertically he would have obtained -hbar/2, so at 120 deg Alice says he should get hbar/4 per our single particle example. But of course, Bob must measure the same value for h that Alice does, so he can't get the fractional value of h Alice says he should (otherwise, Alice would be in a preferred reference frame). Instead, his outcomes at 120 deg corresponding to Alice's +hbar/2 outcomes vertically average to hbar/4 just like the single particle case. And, of course, the data are symmetric so Bob can partition the results according to -*-his-*- +/- hbar/2 outcomes and show that Alice's results satisfy conservation of spin angular momentum on 'average only'. In the end, Alice partitions the data per her +/- hbar/2 outcomes and says Bob's results must be averaged to satisfy conservation of spin angular momentum while Bob's partition shows it's Alice's outcomes that must be averaged. This should remind you immediately of an analogous situation in SR. There when Alice and Bob occupy different references frames via relative motion, they partition spacetime events per their own surfaces of simultaneity and show clearly that each other's meter sticks are short and their clocks run slow. In other words, the mystery of quantum entanglement resides in 'average-only' conservation that results from "no preferred reference frame" (NPRF) giving the observer-independence of h (NPRF + h). And, the mystery of length contraction resides in the relativity of simultaneity that results from "no preferred reference frame" giving the observer-independence of c (NPRF + c). Give up your constructive bias for QM just as is done for SR and physics makes perfect sense. But, the implications for your worldview are profound; you have to accept that physics is most fundamentally about constraints on the 4-dimensional (spatiotemporal) organization of worldtubes per NPRF + c and the distribution of quanta therein per NPRF + h.

[@ryandowney3577]

A lot of the confusion is due to a tiny omission: the same coin in the same box always produces the same animal throughout the thought experiment. This isn't intuitive in the realms of symbolic logic. (I don't think the "NB" solves much, since even it doesn't explicitly state that that output will always be the same if the coin and the box in question are the same.)

[@tomtomspa]

you saved my brain, thanks!

[@Ccaste1967]

Saved my brain too. Thanks Ryan.

[@santanukumaracharya3467]

Quantum is the word that some day Scientists would equate with Cosmic Intelligence. We are waiting for that day to come. Thank you for your interesting talk Dr. Phillip Ball.

[@namrata3282]

Amazing explanation, it did make the topic easier

[@MichaelHarrisIreland]

Thanks for making this video, it's brilliant, it helped clear my head, at least I've got a toe hold on a cliff face of unknown depth or height. "The mind has chasms, cliffs of fall, sheer steep no man fathomed."

[@RedScaledKnight1]

am still slightly confused ; just means i was paying attention. most coherent, concise explanation delivered in a very pleasurable voice. thank you, truly, for making and then sharing this video with us. let us watch and be nourished

[@dhaditya4867]

First of all Thank You so much for taking your time and explaining most of the misunderstood parts but.. the last 6 mins of the video was again not to point it was just facts with no proof and also you forgot to explain why it is 85percentage and the idea or the rules which made it 100 percentage . Thank you

[@hquillin]

I see it as a plug for a very likely Great Book, I think we are in a real world where more money is paid to a CEO of a minor company than any Nobel from Demark. have fun q

[@robertbrandywine]

"Quantum nonlocality" are just words describing a phenomenon that is still spooky.

[@wayneyadams]

I've studied Special Relativity since I was 15, some 59 years ago, and found it to be logical, but to this day even with an M.S. in Physics, I find quantum mechanics, at least the way it is interpreted today, to be odd (spooky, if you like). The difference is that Special Relativity does not have the random unpredictable nature of QM. Even though it works, QM still leaves me with an unsettled feeling.

[@robertbrandywine]

@@wayneyadams I think that's probably because you think humans (smart ones) should be able to understand everything in our universe. Reading Kant's Critique of Pure Reason made me understand that our available logical concepts need not be, and probably aren't, all the logical concepts there are. So until we evolve into higher beings, we are stuck.

[@wayneyadams]

@@robertbrandywine The point of my comment was that QM flies in the face of reason. It's a concept that seems like it can't be true and yet all experimental evidence seems to indicate it is. I agree that our puny little evolved ape brains probably are not at the point where we can truly understand the universe around us.

[@Luke-ih1oc]

@@robertbrandywine say what lol

[@jjbudinski8486]

Great talk, it makes one think. To me it exposes the issue with only having 4 dimensions, X,Y,Z, and t, and it sort of steers one into the idea of extra dimensions, these being the ones of particle interaction. Say A,B,C, and d are dimensions in which very specific particle properties exist or are modified through, and in this dimensional reality distance and time (or whatever they are) are completely different than XYZt. The abstract idea of extra dimensions can make more sense if we can relate them to things in our own tangible dimensions. It may even be possible to map other dimensions based on these "spooky" particle relationships. I've always had an issue with the idea of extra dimensions, the concept makes no sense, but this talk gets one wondering.

[@michaelblankenau6598]

Excellent explanation of a difficult concept . Perhaps explaining how the " rules " of this scenario apply to the quantum world specifically would wrap things up neatly .

[@dnomyarnostaw]

Sometimes you get a lecture that 'clicks ' when the explanation just fits with stuff you have heard before. I was lucky to experience this from this lecture. I nearly 'lost it' at the Alice and Bob box analogy, My big takeaway was confirmation of the 'no spooky action' understanding.

[@igotazackinjabari]

I came here trying to understand what Jada meant by Entanglement

[@wclewis123]

Nice explanation. Puts Bells theorem into context.

[@1996Pinocchio]

Inspired me to watch the whole talk :)

[@iSoloMusician]

I lost it as soon as he mentioned rule 2 & rule 3.

[@seasnek7024]

iSoloMusician yeah I’m not gonna lie i barely grasped his whole demonstration because of rule 2 and 3.

[@damianosharolatridis8497]

The subject is scientific therefore you might need to pause the video and work it on your head. I had to come with this array of results by my self to understand it fully. And its actually an easy concept. Its a video after all. Use the advantage it provides such as pause.

[@ajit_edu]

Before the big bang, all the space time, and energy and mass that we observe today was crushed in a tiny quantum state. So doesn't this mean that entire space is entangled ?

[@hquillin]

have not got a clue and doubt that the person to answer your question is going to see or get entangled with your ? q

[@dnomyarnostaw]

Good point. They WERE entangled, but breaking the entanglement is really easy. Other forces affecting the particles (which are largely photons or electrons) is really easy when other particles and/or forces act on individual ones. Remember, if something affects one particle, there is no "spooky action" on the other particle.

[@ajit_edu]

May be both, after all it is quantum J

[@dnomyarnostaw]

@@ajit_edu They have done calculations on the likelihood, and with inflation, etc the chances of any original particles being entangled is virtually zero.

[@hquillin]

@@ajit_edu to the 21Century reply is I get that it is a quantum i not j

[@zainabalshammari]

I like that you use examples. Thanks.

[@scottterry2606]

Thanks for that. Much clearer.

[@kelly2fly]

Not quite sure if quantum mechanics broke any laws of physic but I do know it broke my brain.

[@zoranvelickovic8814]

Don't worry he just doing remap.

[@paulhumphreys7369]

That was so good...I nearly understood.

[@marekmanini]

I don't think so?

[@paulhumphreys7369]

Marek Manini err no.🙁😂

[@DipakSisodiya]

85%?

[@tjjohn9785]

Clear and concise explanation of a complex phenomena in physics

[@lee_at_sea]

leaps right over explaining why any connection or hidden variable would be needed (as does every video on this topic). no explanation of that at all. if I slice a globe into N/S halves, and send one away, then measure that mine is N, I can know the other is S with no telephone, no hidden info, no secret connection. it's just the other half.

[@brandieboyd2312]

Beautifully put. Well done and bravo to you!!!!!👍👍👍💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚💚 and also, it may seem complicated too many but it is actually very simple. There is also a beautiful love story out of this and that would be love itself

[@guymross]

Thank you for clarifying once and for all that quantum physicists are awful at analogies. :)

[@bertrandmeltz1153]

Why use analogies when you could use cardboards ? kzbin.info/www/bejne/kKbZfGClmZtnbcU

[@jamestheotherone742]

It is intentional. QM has to be shrouded in obfuscation otherwise it would just be a minor theoretical field of statistical mathematics.

[@hquillin]

@@jamestheotherone742 and what is it if it is true and not shrouded. ?? q

[@guymross]

Bertrand Meltz that's great thank you

[@tabaks]

Ummm, no.

[@GB-rf4fu]

You should explain this 85% !

[@9erik1]

basically, the way the experiment is set up, you solve the appropriate quantum mechanics (QM) equations and the 85% comes out naturally. the 75% predicted by hidden variables (HV) is a purely logical approach. the conflicting predictions come from this logical approach vs the QM equations. there are even more rigorous tests of HV vs QM out there, where HV predicts 0% but QM predicts 100%... QM always wins

[@philipball4720]

Yes, see below. It is called the Tsirelson bound, and arises simply from the way Bell correlations are set up: en.wikipedia.org/wiki/Tsirelson%27s_bound

[@jamestheotherone742]

@@9erik1 No. The 85% is from the error factor in the observations. Not actual reality. If you could observe 100%, then you could observe all state variables without influence and QP waveform collapses to a fixed value. It drops out of QM into plain ol' vector mechanics. No more hocus pocus.

[@9erik1]

@@jamestheotherone742 nah what I'm saying by the 100% thing is that there are certain bell experiment setups where HV never permits a certain result, whereas QM ONLY permits that result

[@Huntracony]

@Enter the Bragn’ What kind of conspiracy garbage are you trying to push down our throats here?

[@kiberenigestsebez6633]

Your explantion is clearer, I guess i saw so many videos and read few basics

[@roberte.6892]

Fantastic explanation of a very difficult concept.

[@Anthony-gq7dk]

Well done , a great lecture and well delivered. I loved the glove analogy , excellent and clever. Makes it clear to a novice.

[@somethingirreversib]

Entangled particles act like c++ pointers :). Different variables pointing to the same memory block.

[@johnmackenzie3030]

I love these videos. Its 4 in the morning - ive got insomnia but I have some very very bright physicist chatting to me about Entanglement. How incredible is that. He doesn't need to hear my input (wow spooky action at a distance er... that's spooky man)

[@mathewaugustine2698]

That's a great job of simplification

[@samyakmeshram2205]

I'm here because Martha said 'Quantum entanglement' while explaining a phenomenon. Had to know what it meant!

[@markmd9]

Oh No, the analogy example was awful, not the e explanation! The author should have come with a different example or best would be to explain simply the real experiment. Trying to explain the same bad analogy again in a longer detailed video is pointless!

[@JB_inks]

Should have come, not should have came. Grammar matters.

[@Amani_Rose]

Waaaiiittt Alice and Bob analogy?

[@Amani_Rose]

Maybe it's the way you explained it or maybe it's my ignorance to this matter but Bohr's Copenhagen Interpretation actually makes sense. The whole idea of the spin being uncertain until she measures it. cuz if electrons are constantly moving etc you could also assume their spin to not have a definite state?

[@juanlizarazo2307]

Dear Phil, thank you for making this video. I have a question regarding fields that I hope you could address. In QFT a particle is a wave-like perturbation on a field, the speed of a wave is determined by the media, but the speed of a particle is determined by the source. How these two are reconciled in QFT. QFT reconstructs the particle-like behavior by adding an infinite number of planar waves. However, in experiments we can have a particle traveling with any speed we like (less than c). On the other hand, it is known of waves that their speed is determined by the media on which they travel. I couldn't have a wave on the surface of a pond travel at any speed I like. The speed is determined by the characteristics of the pond. So, how these two are reconciled in QFT. Any pointers of where to find the answer are highly appreciated. Thank you very much, Juan.

[@irondoc4565]

Hi Mr. Philip. I have to say you did such a fantastic job explaining this and it just feels awesome listing to you talk about this topic. I really love physics so much but never gone beyond first year university physics. But I think I have a great real life example of quantum entanglement which I think is really true. I have a little 3 year old daughter. And whenever I think about her I can feel exactly what she is doing. It's totally like the quantum entanglement. When she was a baby every time I would think about her she would start crying. And this was so strong I said to my self I'm going to stop thinking about it. It's hard to explain but in my view entanglement doesn't have a physical "explainable" property to it. But I think a mother/daughter thoughts are entangled. And no matter where she is in the world I can be thinking and knowing exactly what she is doing.

[@michaelblankenau6598]

Utter nonsense

[@tegatobu8577]

I’m starting to love physics man🤩

[@jordancox8294]

Xäp 8 KZbin and a biography of Einstein has me on the way back to university.

[@tegatobu8577]

jordan cox honestly I’m taking an astronomy class which opened my eyes to all of the stem fields and the brilliance of it all. I’m going to be an engineer now

[@aasirafzal2927]

Don't love it once u started loving it u will never ever come out of this physics is addiction

[@proman84]

One question regarding the "action at the distance" part and how it's not a thing. It seems that saying that two particles are the same is overlooking the part that they remain connected no matter the distance between them. Meaning that the factor of the distance not mattering seems to be overlooked or, at least, de-emphasized by simply saying they are one object.

[@kolamunne]

This is good an explanation about entanglement in real physics compared available other explanations which are not very clear in someway. Many thanks.

[@MOSMASTERING]

Awesome teacher and explanation.

[@mischake]

I saw the talk a while ago and didn't understand the boxes. Now you've told it here again... and it makes no sense what so ever as far as I can discern. Truly, I think that people should just admit that they don't yet understand the quantum scale and how things work there.

[@joerock7005]

I could not follow the logic with the boxes. I could not use their rules and get the same results matrix. the rules seemed fairly simple. I must be missing something. Did anyone reproduce the results matrix from their rules? Please let me know.

[@hquillin]

and most humans never will understand something that is correct only 85% time in my opinion. have fun q

[@ThePinkus]

@@joerock7005 Yes, see my reply to Your other post.

[@bearscarf3077]

Best explanation by far

[@Jay-im3qj]

Fascinating subject.

[@lucidmoses]

Keep in mind the pencil through the paper worm hole analogy when I say. This is consistent with quantum particles being 4d items while atoms are the 3d effect of those particles. Like a flock vs birds. Since we are made of atoms we can not see the 4d universe.

[@hquillin]

I predict you may be doing your own paper or thesis or Ted talk if you keep this up,

[@dnomyarnostaw]

That is totally NOT what physicists say. You can entangle, disentangle particles (Electrons or Photons) at will with simple benchtop equipment. There are no special "quantum particles"

[@lucidmoses]

@@dnomyarnostaw If you think you've made a point on my comment then you best reread it because your statement is in no way relevant to what I was talking about.

[@dnomyarnostaw]

@@lucidmoses "quantum particles being 4d items" ..is just nonsense. We are talking Photons and Electrons. Very little else is used as a Quantum particle. Calling Photons and Electrons "4d" is just woo.

[@lucidmoses]

@@dnomyarnostaw ".is just nonsense." Ok, prove it. Or are you just making up assertions. I on the other hand I was careful to summarize and get it right. The least you could do is read what I actually said and argue against that.

[@markjacobson299]

if you think of time-space as a grid laid upon a nondimensional void, then entanglement makes sense. "local" is universal in that sense.

[@robknight9406]

Mark, what is a non-dimensional void, and where does it exist

[@markjacobson299]

@@robknight9406 a nondimensional void? no time. no space. no matter. just symmetry. virtual nothing balanced out by virtual nothing. our universe came out of a nondimensional void (by means of a random quantum fluctuation) and the time space dimension is still unfolding at the edges. the big bang is still happening.

[@willfrank961]

Mark, what is a non-dimensional void and how can I buy one?

[@willfrank961]

Also, didn't think I could lay a time-space grid on my will to live.

[@markjacobson299]

you might get away with it. but, if I was you, i would get someone else to stick their arm in there first and see what happens.

[@biniyamwolde4338]

nice explanation!!

[@PeterPete]

True love is a great example of quantum entanglement where two people can become entangled throughout a lifetime - it's amazing that all we really learn in life is love; what is love, how to love and who we love but nobody educates us about this, not even the Royal Institution!!

[@Elfdogable]

Exactly how do two photons get ‘entangled’ ? Are they entangled indefinitely? Can a photon get re-intangled with a different photon later ?

[@syourke3]

TimeTime Only with a legal divorce from the first photon.

[@photinodecay]

It's just the result of certain types of interactions which have certain constraints based on conservation laws, but certain freedom within those parameters.

[@photinodecay]

I don't think particles can change their entanglement. Once they "interact", there are effectively new particles coming out the other side of the interaction.

[@Elfdogable]

Rahul Jain ok, so it is kinda like a one way function. With this I think the term ‘entangle’ is misleading. Seems like the term should be changed to be more descriptive and consistent. I feel confident I’m missing something here since scientists agreed upon thus term. I’m still puzzled how two entangled particles can be derived from one source particle unless the two are halved from the one.

[@photinodecay]

@@Elfdogable Particle count is not a conserved quantity. A single photon can split into an electron and a positron, for example. Their wave functions are entangled with each other. One particle's values are based on the values in the other equation and vice versa.

[@nickfoxy]

Schrodinger to Heisenberg “so is the cat dead or alive Werner.” Heisenberg to Schrodinger “well Erwin I’m uncertain about that” 🤣

[@xaverneidinger4767]

Such a good English - just supa to hear from somebody that learned english in school - brilliant Mind too !!

[@___Truth___]

I don't know, he has a hard time pronouncing his R's

[@williammorton8555]

Excellent. Thanks you.

[@makersmark5607]

Quantum Entanglement is what happens when physicists try to understand quantum theory.

[@92587wayne]

It is called an abomination

[@beldiman5870]

It also happens when scientists are desperate for getting new research grants.

[@hl236]

Jada Pinkett Smith brought me here.

[@hms9520]

why? from where? what did she say? i am curious

[@juliusholstein2376]

@@hms9520 she was in an entanglement

[@221Dw]

Great news...

[@sallya2202]

🤣

[@stevenrogersfineart4224]

She’s not bright enough :P

[@josephmarsh5031]

My favorite demonstration of entanglement is when you use polarized film to break reality. Step 1: use polarized film to block ~50% of the light coming from a light source. Step 2: use a second sheet of the Same kind of film placed perpendicular to the first to block ~100% of the light coming from the light source. Step 3: use a third piece of the Same polarized film and place it between the other two (currently blocking ~100% of the light) to block ~85% of the light, breaking reality into pieces!

[@Littleprinceleon]

First of all: we have to emphasize that the light gets polarized in some direction from the first filter. The perpendicularity of the second is regarding it's polarization angle! Then if you place the third in any angle over the previous two: no light is miraculously renewed from zero light energy. You have to place the third filter at 45° between the previous two: so you reorient the polarization from the first filter! This new polarization is no longer perpendicular to the second filter (but at 45° angle).

[@josephmarsh5031]

​@@Littleprinceleon True, in between, is correct. But it still beggars belief. Not only that, but every filter you add between the first two that isn't aligned with another filter, decreases the effectiveness of the original two. That's still something that blows my tiny mind!

[@dr.s.choudhury8089]

Going to rewatch the series Dark again to ease my mind off again. I thought that was complex but this is a way more boggling 😬

[@RoGeorgeRoGeorge]

Familiar with the subject, yet I couldn't follow the talk. Probably an out of context edit? Maybe it would be a good idea to leave aside Alice, Bob and weird imaginary boxes with strange cooked-up rules, and just state the facts. Nobody needs coins and rabbits here. Those are just adding confusion. It is not a board game with strange invented rules, it's reality, so start by describing real experiments and their results, and build from there. Only afterwords start discussing what abstract rules might be in place, so we see such experimental results.

[@pansepot1490]

RoGeorgeRoGeorge, not very familiar with the subject but I thought the same.

[@davidwright8432]

The facts are exactly the statistics produced by B & A's devices.

[@andrewtoland1933]

I can think of something that Alice could put in her box

[@joerock7005]

I am also familiar with the subject. I could not follow the logic and get the same matrix. Did he leave out some bit of information or perhaps I did not understand the rules. Was anyone able to get the same matrix?

[@hquillin]

Speak for your self this i needs all the help he can get I married a smile/ have fun q

[@stanleytolle416]

Hold it with the lies. Nobody understands entanglement. The truth is this is what happens. It's spooky, bazaar, can't possibly work that way but it does. That is really our understanding of it.

[@robknight9406]

The truth is that we don't understand what's happening - so there is no way you can say "The truth is this is what happens" The particles are related and have common attributes - but we can't change one and watch the other change accordingly.

[@hquillin]

stanley Tolle a lie, to me, has intent to mislead, I don't see that here. thanks for your point of view you may be 85% RIGHT EVEN far Right/ q

[@sw.7519]

We think spooky because it is way beyond of our understanding. Multiple worlds is a explanation. Who knows.

[@jonathanjollimore7156]

Very cool great explanation

[@roshnirahangdale228]

we have taught that while creating entanglement between 2 particles via photon there is conservation of charge which means if a particle have positive charge the other would have negative charge, there is also conservation of spin which means that if one particle have up spin then the other must definitely have down spin .These r the 2 conditions to justify that 2 particles r entangled or not and there is conservation of charge and conservation of spin because to produce the net effect zero as photons don't have charge as well as spin . But the interesting thing here is to note that that there is no conservation of mass between the 2 particles so as to produce the net effect zero as photon mass is zero. My biggest dought which implies that if there is no conservation of charge that particles (not photons) cant be entangled at all. If anyone get some info about this pls inform me in the replies section.

[@mrshangpa]

I was waiting for the 85%, then I got entangled.

[@Someone-cr8cj]

One take?!? Cheers

[@nathankroeze1412]

if you spin two spinning tops counterclockwise at the same rate in a frictionless environment and supposing perpetual motion is possible then when you observe one top you will always be able to make an inference as to the orientation of the other top without those tops ever communicating anything.

[@DRIFT-WOOD]

Thank you for the most impressive science video I ever randomly clicked on in my Bell inequality KZbin watch later video list. Best description of this topic I have seen for now. "Entanglement flag" is a nice term, in not just one way, I like it.

[@wulphstein]

I keep thinking that quantum waves and ghosts are related, two sides of the same coin. Like yin and yang. It's the only conclusion that makes sense. Remember that nature uses the least action principle. The universe is inheritance lazy. But there is no reason to disallow a complex life form of very low energy content. QM should predict the existence of ghosts. A ghost is a special kind of wave function that has free will, consciousness, but has to creep between potential energy wells to move around. If you don't see it, then you are being intellectually avoidant.

[@thebeast5215]

But the ghost has to be made of something. Specifically, something that interacts with light sometimes. There's no real evidence of ghosts, aside from crackpot supernatural shows and fake videos.

[@larsyxa]

The explaination is always how entaglement works, that has been stated over and over again. What always seems to be passed over is why particles gets entagled?

[@untamedchance9656]

I believe it’s because of energy states. It’s probably easier for two particles nearby each other to be in opposite spins than the same. Opposites attract and similar repels. Opposites are always opposites no matter what so they become linked

[@KipIngram]

"Shared information," "quantum nonlocality," "spooky action at a distance." Asserting that those are different feels like playing with semantics to me. Any way you slice it, the effect is getting from A to B faster than light. Recently there's been the whole ER=EPR thing, equating entanglement to "wormhole like" connectivity between places in spacetime. Well, again that's just another angle to approach the same point from - it implies a "shortcut" from A to B, but that's just tinkering with distance rather than tinkering with time. The end result is the same. The best explanation I've seen is in Christian Baumgarten's paper, "How To (Un-) Quantum Mechanics." He models reality as an arbitrary collection of state variables that are functions of *time only*, and then makes one assumption: that there exists a single function of those variables that is conserved as the variables change with time. The mathematical analysis that follows shows that three spatial dimensions and most of the modern laws of physics "emerge" as necessary consequences. Some interactions that occur within this framework depend on those emergent spatial dimensions, and those are limited to a maximum speed (not one put in by hand - that speed limit is also a consequence of the analysis). But other interactions do not depend on the spatial dimensions; they have nothing to do at all with space. So they are not subject to any such speed limit. This is where the "instantaneous" connection between degrees of freedom comes from in Baumgarten's picture of the world. Note that the "time parameter" that these variables depend on is not any particular observers "personal time" - observer time would enter in as another emergent property. The "master time variable" is a single independent thing, and there's no funny business about it. Also note, though, that this master time variable isn't necessarily "accessible" to physical observers residing inside this "reality." It's an attribute of the model only.

[@starrising491]

Excellent video!

[@TigerDan04]

Nice video! Also, I'm happy to give you a haircut for free!!!

[@americalost5100]

"When we observe it..." Isn't this always the misleading phrase? Shouldn't it be "When there is an interaction..."? Whether we observe it or not? Whether we measure it or not? Why imply that we somehow have to be part of what makes a wave function collapse? When surely they collapse all the time all over the universe far beyond any possible role we might have in them doing so...

[@SanchitShettyTantraYoga]

I guess because it collapses 'whenever' we observe it. That is what prompts d phrase 'when we observe it'. It is not misleading bcos observer collapses the wave function does not imply that 'sumthing' else doesn't collapse it. It simply implies that 'observer collapses the wave function.'

[@drphosferrous]

Ive read that this quantum probabity becomes fixed at any measurement,with or without a conscious observer.

[@SanchitShettyTantraYoga]

@@drphosferrous yes!! And that maybe completely true. But i guess the thing is a conscious observer collapses it 'for sure'!! And thts wat needs to be looked at too i guess.

[@drphosferrous]

@@SanchitShettyTantraYoga i suspect that when "information" is better understood in physics,general relativity will reconcile with these quantum spookularities.

[@SanchitShettyTantraYoga]

@@drphosferrous yea mayb. But whats interesting is that even though science may not accept the entitative existence of the witnessing principle, it is still interesting to understand that this Universe with all its complexity had the potential to create and also indeed created an observing principle like d human mind wich can observe and understand information. I think a time will come when instead of trying to focus on the small particle which we are trying to understand, humans wud start focusing on tht 'entity' , tht principle wich is actually understanding information!!! I dunno for sure though but sure looks like it wud go that way!

[@stevenrogersfineart4224]

I love this.

[@keithbowden4248]

If you have 2 electrons and one is observed to be left spin then you know the other is right spin, assuming this is a correct interpretation, is the determination of the spins confined to the sub atomic level and if yes then, at the sub atomic level can these same 2 electrons be 299 792 458 m / s apart? How is the quantum entanglement of these 2 electrons extrapolated to universe size by physicists? In the Alice / Bob example you present when Alice knows the glove is left handed, she also knows Bob's glove is right handed but only Alice knows this as Bob may not have looked at the glove to know which he has? (if that makes sense)

[@nyrdybyrd1702]

01:45 🤬 telling me I don't need to know about spin/angular momentum.

[@llawliet8751]

do you?

[@SuperflyBri]

There's a dead cat in one of the boxes.

[@sonpopco-op9682]

or possibly both.

[@jainalabdin4923]

When I think about spin up and spin down, I think of a seesaw, where one end spins about a pivot, so that the opposite end is always the inverse and never the same. So I have a question: If I push up at one end of an arbitrary seesaw, does the other end go down instantly? Is there a delay in the force applied or does this force travel at a finite speed? What if this pivot approaches an infinitesimal point in size and the seesaw is contructed by an infinitesimally thin line of arbitrary length passing through the pivot - would pushing one end up instantly push the other end down? If there are two entangled electrons analogous to a pivoted seesaw as above, maybe we should be looking for the pivot?

[@davsaa33]

Your comment made me think of another way you can think of what you said: If we have a 1 meter stick, the moment I push it from one end, the other end moves immediately. Now, what if we had a 1 km stick, pushing from one end, again affects the other end immediately. Anyone on the other end, would see the stick move immediately as soon as I push or pull it no matter the distance.

[@Littleprinceleon]

For both of you: the force applied travels through the molecules of the object at speed with maximum of that of the EM waves

[@jainalabdin4923]

​@@Littleprinceleon Thanks for the answer to the thought experiment. I considered your reply to be accurate, as I was thinking the same when I posted the question way back then. However, since the spin up/ spin down happen instantly, the maximum speed of EM through the material cannot be what is happening as this isn't instantaneous. I'm thinking of a 'time pivot'. If you consider a pair of anti-matter/ matter particle creation, which happen instantly, and think of the anti-matter as the same particle as the matter particle but travelling backwards in time, then with a similar principle we can also apply this to entangled spin up and spin down as the same particle. When spin is observed with two entangled particles, one can consider the other as the same particle but travelling back in time. Both types of systems are connected with a 'time pivot' and are the same particles but with the 'other' particle travelling back in time. These systems when observed, collapse the wavefunction and give the impression that they are happening 'instantly' and the mechanism travelling faster than light/ EM.

[@danzuck8936]

You have convinced me that non-locality connects to 85%, but I guess I must buy your book to understand why and how. So sad, since my life circumstance renders that purchase too inconvient. But thanks for what you did make clear, teaser that it is.

[@dimitri1462]

Not sure why physics has become so dogmatic in the last 20-30 years. What if Special relativity doesnt apply in all cases? Maybe space/time is an illusion and there is really no separation between the entagled particles!? We assume same rules for Gravity apply everywhere in the Universe with the same constants and then we 'invent' Dark Energy/Matter which we havent been able to detect. Same way we 'invented' the INLATION theory (post Big Bang). I hope the young generation of Physicists/Mathematicians is looking at other options to explain some of these Quantum phenomena without the Dogmatic assumptions.

[@irn2flying]

Well said...It seems it's the physicists who "think outside the box" are the ones who make the breakthroughs. They/we are obviously missing something. (a lot actually. lol). A very complicated universe underneath the veil of apparent solidity : )

[@udaybhanuchitrakar8812]

@dimi dimitri sekharpal.wordpress.com/2016/10/16/spaceless-and-timeless-god-and-quantum-entanglement/

[@sonpopco-op9682]

Many younger physicists are coming up with new & better theories' unfortunately like any other institute, the mindset & beliefs of established scientists are very hard to change. Often changes only comes about when all the old farts die off.

[@syourke3]

Quantum mechanics is very Bohring!

[@scopovita]

That means the edges of the black whole that connect to empty space are a massive dissipation of energy which causes the black whole to pulse once the void dissipation energy builds enough to hit the resonance frequency the black whole sends out, possibly.